lvalue list optimizations

[John W. Eaton]

On  5-Aug-2010, Jaroslav Hajek wrote:

| as some of you may noticed, I recently implemented a simple method of
| propagating lvalue list information into functions. Within m
| functions, the isargout function can detect which outputs are being
| ignored using ~ and possibly skip certain computations. This is a
| generalization of the usual conditional output evaluation using
| nargout. The latter is usually sufficient, but there are some
| functions where output argument order is dictated by consistency and
| omitting a leading output simplifies the operation. In Octave's
| library, sortrows and histc are an instance.
| 
| Now I would like to make this information available to the DEFUNs. The
| cleanest way is to simply pass an additional argument. Is it OK to
| change the signature of a DEFUN? The macros DEFUN and DEFUN_DLD would
| be preserved (and declare the extra argument as ignored).

I don't object to an additional macro that accepts the new parameter
as long as the old ones continue to work as they do now.  I assume you
would only use the new macro(s) in cases where the extra parameter is
actually needed, correct?

jwe